2G BEGi FPR fuel pressure not increasing under boost!?

[Brad Bell]

So I have a BEGi Adjustable fuel pressure regulator installed on my 1999 eclipse gs 420a turbo. Under 8psi I am supposed to have a raised fuel pressure of 75-80psi. I currently have the base fuel pressure set to 50psi. With the signal line attached to a tee between the intake manifold and the blow off valve. No matter what I set the fpr to however, I can't get the fuel pressure to rise under boost. Even if I turn the brass needle bleeder valve all the way in! I have a good fuel pump installed, when ever I turn on the car it primes to around 80psi on the gauge. The fuel pressure actually goes down whenever I step on the gas, when I let off it goes back to the set 50psi. What is going on? I'm not sure whether to replace the fpr or the pump?

 

[ThunderChild]

How are you monitoring fuel pressure? are you monitoring while roving under boost?

Free revving the motor will not build you boost usually. also, the fpr should have its own dedicated vacuum source. it also sounds like you have a FMU, not AFPR, since the pressure change under boost isn't 1:1.

Being that 420a 2gs have a returnless fuel system from the factory, have you converted to return-style?

 

[dsmcrzy]

Being that 420a 2gs have a returnless fuel system from the factory, have you converted to return-style?

Not completely true. The stock fuel pressure regulator on 96-99 non turbos is back by the fuel tank near the filter. 95's are slightly different, they might have the returnless system though I don't remember off the top of my head. So under the hood 96-99 does look like a returnless fuel system.

It does sound like an fmu though. Post some pics OP.

 

[Brad Bell]

How are you monitoring fuel pressure? are you monitoring while roving under boost?

Free revving the motor will not build you boost usually. also, the fpr should have its own dedicated vacuum source. it also sounds like you have a FMU, not AFPR, since the pressure change under boost isn't 1:1.

Being that 420a 2gs have a returnless fuel system from the factory, have you converted to return-style?

Yes there is a return coming from the regulator back to the tank. I am monitoring the fuel pressure by an electronic fuel pressure gauge. It is however an fpr, it is setup by running a fuel line from the fuel rail, them to the regulator, then a return back to the tank. Your supposed to set a base fuel pressure by the center set screw, then adjust a bleeder valve with a one way check valve attached to it. No matter how I set the regulator though, fuel pressure won't rise under boost. I can go under boost no problem, but it leans out and starts jerking. I just want more pressure under boost. Not sure what the problem is? There isn't any free ports on the intake manifold for the signal line, so I have to tee off something.

 

[Brad Bell]

Not completely true. The stock fuel pressure regulator on 96-99 non turbos is back by the fuel tank near the filter. 95's are slightly different, they might have the returnless system though I don't remember off the top of my head. So under the hood 96-99 does look like a returnless fuel system.

It does sound like an fmu though. Post some pics OP.

Here are some pics. This is the same model I have.

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[ThunderChild]

If you have a return-style fuel system setup, then I don't see why you need a check valve inbetween your afpr and vacuum/boost source.

It sounds like the afpr may not be functioning correctly, and possibly has a blown/ripped diaphragm.

Does the base pressure change when you adjust the main screw? also, does the fuel pressure go down when you hook to vacuum?

I would say to remove the check valve or at least verify it's orientation is correct.

 

[Brad Bell]

If you have a return-style fuel system setup, then I don't see why you need a check valve inbetween your afpr and vacuum/boost source.

It sounds like the afpr may not be functioning correctly, and possibly has a blown/ripped diaphragm.

Does the base pressure change when you adjust the main screw? also, does the fuel pressure go down when you hook to vacuum?

I would say to remove the check valve or at least verify it's orientation is correct.

Thanks for replying! Yes I can change the idle fuel pressure with the center screw, that works just just fine. When I detach the signal hose nothing happens, the fuel pressure doesn't change with or without the vacuum line attached, not sure why. I only problem I'm really having is the fuel pressure doesn't go up with the boost, so I get a lean mixture. I'm thinking the regulator is just damaged and I should just buy a rebuild kit for it.

 

[ThunderChild]

My thought is the check valve is causing part of the issue. if the fpr doesn't react to vacuum then either the check valve is not working/installed incorrectly, or the fpr is damaged/defective.

Personally id get an aeromotive or fuel lab AFPR. once you set base fuel pressure with the vacuum disconnected from the afpr, it will lower fuel pressure while the car is running and the vac. line is hooked up, then under boost it should increase fuel pressure.